Actually, Oracle light is meant to do excatly what you are describing. A low maintenance db on devices that travel.
Take a look. For details on what Oracle supports of replication (which is the term Oracle uses for DB-DB sync – not DB-user) check out the RDBMS manual for replication. There are restrictions based on your data structures and operations you wish to do. Trying to give you a general answer here would not serve much purpose.